Question

Mention the events that lead to the development of placenta
during pregnancy in human females.​

Answer 1

Answer:

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Explanation:

Placental development starts with the first contact of the outer shell of a developing blastocyst with the uterine mucosa. This newly established contact zone of two organisms develops rapidly and continuously during pregnancy and controls feto­maternal exchange. The functional purpose of fetomaternal exchange of nutrients, gases, and waste substances is common to all placentas. The structure, type of interdigitation, and grade of fusion of the fetomaternal layers constituting the various placentas vary considerably between mammalian species.

According to this definition, human placental development starts with attachment of the blastocyst to the uterine surface epithelium at the time of implantation around 6 to 7 days after conception and progresses rapidly during invasion of the endometrium. At this stage, the blastocyst consists of an outer single layered epithelial cover, called the trophoblast, and of an inner cell mass, called the embryoblast (Figure 10-1, A). The trophoblast is the direct precursor of the epithelial parts of the fetomaternal barrier of the placenta, whereas the embryoblast contributes placental mesenchyme and the fetal vascular system